Giant 20' x 3' x 2' router build

[EddyCurrent]

what are the best methods for tensioning timing belts on to steppers. I have slots for adjustment but need some sort of screw type adjuster to get the belt relatively tight. Cant seam to find much on here.

Section 10 page 45.
http://file.lasersaur.com/docs-third...ming_Belts.pdf

I just used the same technique as putting an alternator belt on, stick a large screwdriver in behind the motor and lever it out until the belt is at the 'correct' tension, now tighten the bolts.

[charlieuk]

i guess that keeps things simple! the pulleys i have have two grub screws for securing however the shaft is totaly round, whats best to do there? put a flat for them or drill a hole or something? cheers charlie

[EddyCurrent]

i guess that keeps things simple! the pulleys i have have two grub screws for securing however the shaft is totaly round, whats best to do there? put a flat for them or drill a hole or something? cheers charlie

Use two grub srews M4 will do, these MUST be 90 degrees apart around the pulley boss (i.e. NOT opposite each other). File a small flat on the motor shaft for one of these screws only. Where the flat is, use a flat bottom grub screw, for the other screw grind it to a point so it digs into the shaft once tightened.

[charlieuk]

cheers many thanks thats great will get on to that

[Clive S]

The way I have done mine is to put a copper plug (pad) into the grub screw hole. I have done this by using a bit of solid core earth wire from twin&earth cable just lightly swash it with a hammer and then cut a piece off that will fit down the hole so that the flat bit is on the shaft then just tighten the grub screws. That way you don't mark the shaft.
I have found that it is not necessary to put a flat on the motor shaft. ..Clive

[EddyCurrent]

The way I have done mine is to put a copper plug (pad) into the grub screw hole.

Im sure the locknuts for my ball screw BK blocks had a grub screw arrangement like that.

[Clive S]

Im sure the locknuts for my ball screw BK blocks had a grub screw arrangement like that.

Yes all mine did as well it's a common way of fixing as it does not damaged the shafts so that makes them easy to remove later if necessary. ..Clive

[charlieuk]

belts arrived, i had to go with 5 teeth less on the motors to get it to fit unfortunately well unless the belts stretch a fraction as it is right between sizes.

[charlieuk]

I mentioned it in a post earlier that i am geting a small amount of flex from the main back uprights which for the surfboards really isn't a problem as the load on the machine will be close to nothing cutting foam however i would like to try and reduce it as much as posable. I have been wondering about two options the first being bolting a pice of 90deg angle steel to each leg ( i cant get large enough channel or T section) and the second idea was to fill each of the current aluminium legs with a resin/granite mix or maybe even a concrete mix which i have been reading about which may help in other ways as well.

Can any one give any suggestions as to what may be best?

many thanks

[charlieuk]

any one got any ideas to the above?